Rubber vulcanization and product thereof



Patented July 21, 1925.

UNITED STATES 1,546,877 PATENT OFFICE.

MORRIS L. WEISS, 0F NEWARK, NEW JERSEY, ASSIGNOR T0 DOVAN CHEMICAL COR- PORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

RUBBER VULCANIZATION AND PRODUCT THEREOF.

' No Drawing.

To all whom it may concern:

Be it known that I, MORRIS L. WEISS, a citizen of the United States, residing in the city of Newark, county of Essex, State of New Jersey, have invented certain new and useful Improvements in Rubber vulcanization and Products Thereof, of which the following is a full, clear,'concise, and exact description.

This invention relates to a process for vulcanizing rubber and similar vulcanizable materials and to the products obtained thereby, being more particularly directed to the acceleration of vulcanization by a class of organic accelerators.

One of the objects of the invention is to provide 'a simple, efiicient process of vulcanization employing an accelerator which shall be more active and shall produce a higher tensile strength than similarly compounded rubber employing as an accelerator one of the parent substances from which an accelerator of the present invention is-derived. By the term more active, as above employed, I mean an accelerator adapted to function at a lower temperature or in a shorter time, or both.

The invention accordingly comprises a process for vulcanizing rubber which includes vulcanizing the rubber in the pres ence of the reaction product of a guanidine, preferably disubstituted, anda 1 mercaptobenzo-thi-azole. The reaction product mentioned may be represented by the following formula:

BHN (5) S C=NH.H s c i BEN obtained by use of guanidine unsubstituted,

or R may represent radicals such as the aromatic radicals including phenyl, tolyl,

Xylyl, cumyl and naphthyl or combinations of these radicals such as phenyl-tolyl where one B is phenyl and the other R is tolyl; tolyl-cumyl and so on. Where the phenyl group is used for substituting each R, the reaction product would result from the use of diphenyl guanidine. The positions Application filed February 7, 1925. Serial No. 7,705.

3-4 -5--6 may be occupied by hydrogen or substituting alkyl radicals.

Example 1 One embodiment of the invention is as follows:

100 parts by weight of pale crepe rubber are combined by milling with 5 parts by welght of zinc oxide, 3.5 parts by weight of sulphur and 1.0 part by Weight of the reaction product of diphenyl guanidine with 1 mercapto-benzo-thiazole. The compound is placed in a mold and heated at 20 pounds steam pressure for twenty minutes, at the end of which time a satisfactory vulcanization is effected. The rubber so vulcanized had a tensile strength of 5332 pounds per square inch and an elongation of 800%. The results have been checked by parallel series of tests. I

In my Patent No. 1,4111231, I have described the process of vulcanizing rubber in the presence of diphenyl guanidine, and I have tabulated below the tensile strength and elongation obtained by using diphenyl guanidine as an accelerator using the same proportion of this accelerator and other ingredients, as indicated in the example above.

In an article in the Journal of Industrial and Engineering Chemistry, Vol. 15, No. 10,

page 1011, Sebrell and Boord describe tests employing 1 mercapto-benzo-thiazole. I have tabulated below the data secured by vulcanization with diphenyl guanidine, 1 mercapto-benzo-thiazole and the reaction product of diphenyl guanidine and 1 mercapto-benzo-thiazole, using the same for mula as the above example Rgacfign prodi Dipheuyl uc any 1 mercapto-benzo-thlazole guamdme and guamdme 1 mercaptobenzo-thiazolo Steam Tensile Tensile Tensile pressure Time pounds Elongg Elong Elong per gatlon square gatlon square gation Square 3 35 inch inch inch Per cent Per cent Per cent 20 20 960 2, 200 Set cure but too 800 5, 332

. soft 0 test 30 20 890 2,425 1, 035 1, 715 745 5, 170 40 20 840 2,900 990 2 205 715 4, 625 5 40 Set cure but too Set cure bu too 810 5, 000

soft test soft to test 10 40 890 2, 295 1, 000 2, 170 730 4, 745 15 40 855 2, 390 2, 605 680 4, 260

It will be seen from these tests that the by weight of sulphur and 0.5 parts by tensile strength of the vulcanized rubber weight of the reaction product of diphenyl compounds obtained by the use of the reguanidine and 1 mercapto-benzo-thiazole. action product of diphenyl guanidine with The compound is placed in a mold and heat- 1 mercapto-benzo-thiazole are greatly ined for the lengths of time and at the steam creased. So far as I am aware, the tensile pressures indicated in the following table strength, namely, 5332 pounds per square inch, obtained when employing the process steam Tensile given in Example 1 is the highest tensile pressure pounds strength that has been obtained for a soft Time 53 ggg sgfr vulcanized rubber. 5:3 fndll It Wlll be observed that the proportlons of the ingredients given in the above example 10 40 880 3 820 may be followed as desired. The following 1 g 33 examples represent embodiments of the 1ni 40 845 1 ventlon using smaller quantities of sulphur and of the preferred accelerator thus given above The results of these tests show that over a range of from 10 to minutes at 40 pounds steam pressure per square mch, the elongationv and tensile strength are almost constant, giving a very flat curve of cure. \Vith the low quantity of sulphur employed the products resulting do not bloom and in addition they are highly durable. These products are particularly adapted for use in automobile tubes and for similar uses.

The accelerator employed in the examples given is preferably prepared as follows:

Example 52 100 parts by weight of pale crepe rubber are combined by milling with 5 parts by weight of zinc oxide, 3.0 parts by weight of sulphur, 0.5 parts by weight of the reaction product of diphenyl guanidine with 1 mercapto-benzo-thiazole. The compound placed in a mold and heated for the lengths of time and at the steam pressures indicated in the following table ;the results being as indicated 1 molecular equivalent of 1 mercapto- Steam Tensile b enzo-thiazole is dissolved in a Water solu- Time 353%: Elqngav poggd tion of 1 molecular equivalent of caustic fg s uare soda. lo th s solution at room temperature nc is added while stirring a water solution of diphenyl guanidine hydrochloride. A pre- }g 38' $2 cipitate occurs which is filtered and washed 30 40 785 41170 free from salt and dried. The reaction which here occurs appears to be as follows:

Example 3 100 parts by weight of pale crepe rubber,

5 parts by weight of zinc oxide, 2.0 parts Then CQHNH S"-- (5) C H NH\ /S"" (5) C=NH.HCl+NaSC C=NH.HSC l +NaCl. cmmH N- 4 C H Nfi un 4 The accelerator may also be prepared weight of diphenylguanidine in alcoholic soby heating together one molecular weight of lution and allowing the product to crystal- 1 mercapto-benzo-thiazole and one molecular lize out, the reaction being The product obtained by either of the during milling nor does it impart objectionreactions given is a white crystalline mateable odor to the finished product. It may rial having a definite melting point (about be ground to a very fine powder which per- 170 Q). It is non-hygroscopic and nonmits it to be easily compounded with rubpoisonous. It gives offno poisonous fumes ber. It is perfectly stable under ordinary conditions. It is practically insoluble in cold Water, slightly soluble in hot water, soluble in alcohol and other organic solvents. It will be understood, as pointed out above, that other materials than diaphenylguanidine may be employed to react with a 1 mercapto-benzo'thiazole. It will also be understood that hydrogen in the ring in the formula for mercapto-benzo-thiazole may be substituted by various other groups. It has been found that instead of zinc oxide other bivalent metallic compounds may be used, if desired. It will, of course, be obvious that other compounding ingredients may be emplo ed.

aving thus described my invention what I claim and desire to secure by Letters Patent is:

1. A process for accelerating the vulcani zation of rubber or similar materials which comprises vulcanizing the rubber in the presence of a reaction product of a guanidine and a 1 mercapto-benzo-thiazole.

2. A process for accelerating thevulcanization of rubber or similar materials which comprises vulcanizing the rubber in the presence of a reaction product of a disubstituted guanidine and a 1 mercapto-benzothiazole.

3. A process for accelerating the vulcanization of rubber or similar materials which comprises vulcanizing the rubber in the presence of the reaction product of an aromatic disubstituted guanidine and 1 mercapto-benzo-thiazole.

4. A process for accelerating the vulcanization of rubber or similar materials which comprises vulcanizing the rubber in the presence of the reaction product of diphenyl guanidine and 1 mercapto-benzo-thiazole. 5. A process for accelerating the vulcanization of rubber or similar materials which comprises mixing with the rubber a compound of a bivalent metal, sulphur and a reaction product of guanidine and a 1 mercapto-benzo-thiazole and vulcanizing the rubber,

6. A process for accelerating the vulcanization of rubber or similar materials which comprises mixing with the rubber a compound of zinc, sulphur and the reaction product of diphenyl guanidine and 1 merca to-benzo-thiazole and vulcanizing the ru ber. v

7. A process for accelerating the vulcanization ofrubber or similar materials which comprises combining approximately 100 parts rubber, approximately 1 or more parts zinc oxide, approximately 2 parts or more of sulphur and approximately 0.5 or more of the reaction product of diphenyl guanidine and l mercapto benzo-thiazole and heating the combination at 20 or more pounds per square inch steam pressure until vulcanized.

8. As an accelerator of vulcanization, a substance having a formula RNH s 5 \C=NHHSC/ RNH/ N- 4 9. As an accelerator of vulcanization, a substance having a formula ENE s 5 \C=NHHSC/ RNH (1)\N 4 where R is an aromatic radical.

10. As an accelerator of vulcanization, a substance having a formula where R is phenyl.

11. A vulcanized rubber derived from rubber combined with a reaction product of diphenyl guanidine and a 1 mercapto-benzothiazole.

12. A Vulcanized rubber derived from rubber combined with a disubstituted guanidine and a 1 mercapto-benzo-thiazole.

13. A vulcanized rubber derived from rubber combined with the reaction product of diphenyl guani dine and 1 mercapto-benzothiazole.

14. A vulcanized rubber derived from rubber combined with a zinc compound, sulphur and the reaction product of an aromatic disubstituted guanidine with 1 mercaptobenzo-thiazole.

15. A vulcanized rubber derived from rubber combined with zinc oxide, sulphur, the reaction product of diphenyl guanidine and 1 mercapto benzo thiazole.

MORRIS L. WEISS. 

